Presently I'm not using any FB meta tags. The <meta property="og:
Generally, in what way can they benefit besides FB's categorization of site?
Anything in the way of SEO? Is this Indirectly?
Facebook's meta data is extremely useful for optimizing your social presence to the point where any public page or item really should have it. With this data you're telling Facebook everything from the category to nature of the page, the image to show when your page is shared. Without it they're scraping and guessing which is far from ideal. The depth and nature of fields varies by category with items like location on a business listing
"It is currently designed for Web pages representing profiles of real-world things — things like movies, sports teams, celebrities, and restaurants"
What about informational sites? Is it really suited for these?
Open graph works with, and is useful for, every type of site... unless you don't care what information shows up when someone shares your url. They simply have more going on for certain actions that have logical interactions (i.e. going to a place, reading a book, buying an item).